Packaging of food products is one of the most important stages of the food supply chain. Nano-size materials for packing food substances with appropriate properties result in better packaging performance and longer food shelf-life. In this review, the application of ZnO nano-size in active packaging of foods is discussed to identify gaps in applications for food packaging and safety. First, the crystal structures and morphologies of modified ZnO nanoparticles (ZnO NPs) are presented, and their synergistic effects on antimicrobial activities are discussed. This review also provides an overview of antimicrobial packaging containing ZnO NPs with a focus on preparation methods, antimicrobial mechanisms, and recent progress in packaging applications. The generation of reactive oxygen species (ROS) is the primary antimicrobial mechanism, which can be varied depending on morphology and size. Generally, ZnO NPs can inactivate fungi or Gram-positive and Gram-negative bacteria growth, which reduce the risk of cross-contamination, thereby extending the shelf life of products. Notably, the health concerns and hazards regarding the safety and migration of ZnO NPs application are also elaborated. Unintentional migration, inhalation, skin penetration, and ingestion may result in human health hazards. Therefore, to provide safety regulations, further investigations such as case by case study are recommended. KEYWORDSZinc oxide nanostructure; shelf life; safety; antimicrobial activity; food packaging CONTACT Jongchul Seo

Edible films and coating materials are commonly used as appropriate packaging materials to extend the shelf life of fresh food. Due to all their properties, edible film and coating materials have been received much attention. They are biodegradable, edible, and good barrier against environmental parameters; thereby, they could carry and deliver food additives protecting food quality. Hydroxypropyl methylcellulose (HPMC), a cellulose derivatives, can act as an excellent film‐forming agent for coating food produces. The aim of this study was to provide an overview of the HPMC properties and investigate the effects of various additives on its film‐forming properties, such as rheological behavior, water vapor, and gas permeability, as well as mechanical, optical, antioxidant, and antimicrobial properties, with a focus on the recent progress and outputs, which has been recently published. Hydroxypropyl methylcellulose is prone to be commonly used as an advanced film‐forming and coating materials for the sake of well miscibility with a wide range of organic and inorganic materials. However, this polymer requires further improvements regarding moisture susceptibility and thermal properties.

A series of PLA/ZnO bionanocomposite films were prepared by introducing positively surface charged zinc oxide nanoparticles (ZnO NPs) into biodegradable poly(lactic acid) (PLA) by the solvent casting method, and their physical properties and antibacterial activities were evaluated. The physical properties and antibacterial efficiencies of the bionanocomposite films were strongly dependent on the ZnO NPs content. The bionanocomposite films with over 3% ZnO NPs exhibited a rough surface, poor dispersion, hard agglomerates, and voids, leading to a reduction in the crystallinity and morphological defects. With the increasing ZnO NPs content, the thermal stability and barrier properties of the PLA/ZnO bionanocomposite films were decreased while their hydrophobicity increased. The bionanocomposite films showed appreciable antimicrobial activity against Staphylococcus aureus and Escherichia coli. Especially, the films with over 3% of ZnO NPs exhibited a complete growth inhibition of E. coli. The strong interactions between the positively charged surface ZnO NPs and negatively charged surface of the bacterial membrane led to the production of reactive oxygen species (ROS) and eventually bacterial cell death. Consequently, these PLA/ZnO bionanocomposite films can potentially be used as a food packaging material with excellent UV protective and antibacterial properties.

No abstract

No abstract